1. Field of the Invention
The present invention relates to modified tractor hitches and modified guides on the implements for receiving the tractor hitches. More particularly, the invention is a modification of a standard 3-point hitch on agricultural tractors, and a corresponding modification of the pinning structure (i.e., guides) on the implements. The modification allows the tractor operator to align and automatically connect the implement pinning area to the tractor hitch by simply backing the tractor into the implement.
2. Description of the Related Art
Various self-aligning structures for connecting a pulling vehicle (tractor) to a pulled vehicle (implement) using a three-point hitch are known in the agricultural field. In accordance with the standard specification set by the American Society of Agricultural Engineers (ASAE), the three-point hitch used in agricultural tractors includes two lower side arms and an upper arm, each arm having a link (an opening) at its end for connecting to corresponding pinning areas on implements. After the hitch is aligned with the corresponding pinning areas, latching pins are inserted to hold the tractor hitch securely to the implement.
There is a need, however, for a structure that permits the tractor hitch to automatically engage the corresponding pinning areas, i.e., to automatically engage the latching pin with the corresponding hitch links when the hitch is aligned.
A discussion of the related art follows.
U.S. Pat. No. 2,871,029, issued to Demarest on Jan. 27, 1959, teaches a tractor hitch for facilitating hitching a tractors to a trailer. U.S. Pat. No. 2,973,971, issued to Oddson on Mar. 7, 1961, teaches a coupling and alignment mechanism for tractors and trailers.
U.S. Pat. Nos. 3,912,119, issued to Hill et al. on Oct. 14, 1975, U.S. Pat. No. 4,350,362, issued to Landers on Sep. 21, 1982, U.S. Pat. No. 4,560,183, issued to Cook on Dec. 24, 1985, and U.S. Pat. No. 4,991,865, issued to Francisco on Feb. 12, 1991, all teach self-aligning trailer hitches. U.S. Pat. No. 5,009,446, issued to Davis on Apr. 23, 1991, teaches a self-aligning coupling for aligning a tractor link prior to connecting the tractor to an implement.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a modified tractor hitch and corresponding modified implement pinning structure solving the aforementioned problems is desired.
The present invention is a modification of a three-point tractor hitch as well as a modification of the corresponding pinning structures on an implement. Implements, for example, include harrows, stump grinders and plows. The tractor hitch is modified to include outwardly extending bushings at the link openings located at the ends of the two side arms of the hitch. The bushings engage with the modified pinning structure to latch the tractor hitch to the implement.
The modified pinning structures on the implement include a spring-loaded latching pin that automatically passes through the link opening when it is in its aligned position. Centering brackets are provided for horizontally aligning the links and a spring-loaded leveling block is provided for vertical alignment, which occurs when the tractor is backed into the implement.
The latching pin in the pinning structure of the implement is spring-loaded to be biased toward an extended position, i.e., to latch with the corresponding link opening. Before latching the tractor hitch to the implement, however, the latching pin is set in a retracted position by pulling the pin outwardly using a handle. When the latching pin is set, its tip rests against the side of the leveling block. Then the tractor is moved in a reverse direction to back the two hitch side arms toward the pinning structure of the implement to engage the link bushings with the pinning structure. The hitch side arms enter the corresponding centering brackets (one set on each side of the implement) and then abut the corresponding leveling blocks.
When the link openings at the ends of the hitch side arms are in proper alignment, then the latching pin automatically engages the link opening of the tractor hitch side arm, by passing through the link opening under bias pressure by a latching pin spring. This latches the tractor hitch to the implement pinning structure, thus connecting the tractor to the implement. A safety retainer pin can then be inserted into the hole at the tip of the latching pin.
Accordingly, it is a principal object of the invention to provide a modified tractor hitch and corresponding modified implement pinning structure including a spring-loaded latching pin that automatically latches the tractor hitch to the pinning structure.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.